There is “not a bottomless pit of money” to be spent on increasing workers’ pay, Transport Secretary Mark Harper has warned the RMT union – as rail staff undertake further strike action today.

Mr Harper told Sky News “there is a fair and reasonable pay offer on the table” and said it is “deeply unhelpful” that RMT members have chosen to continue strikes this week rather than holding further discussions in an attempt to end the dispute.

“It’s not a bottomless pit of taxpayers’ money here,” he said.

“The taxpayers put a huge amount of investment into the rail industry over the last few years when it was hit with huge impact from the pandemic when people weren’t travelling.

“And I think you’ve got to have an offer that’s fair to the people that work in the industry, but it’s also fair to the taxpayer that’s picking up the tab – and that’s the balance that we’re trying to strike.”

‘Significant disruption’ as people return to work – strikes latest

About 40,000 members of the RMT union from Network Rail and 14 train operators are taking industrial action today, tomorrow, Friday and Saturday – meaning most services nationwide will not run.

Train drivers are also set to stage a one-day walkout on Thursday, meaning the UK’s rail network will be crippled throughout the first working week of 2023.

Passengers have been urged to only travel if necessary.

Speaking from a picket line, RMT boss Mick Lynch told Sky News a deal is “achievable in the next few days”, adding that “the companies know what they need to do”.

Mr Lynch said his union members need “a settlement that addresses all of the issues” and warned they may “ballot again” if an agreement is not achieved.

“Our proposals and our needs are quite modest in this dispute,” he added.

Mr Lynch also repeated his claim that ministers were “undermining efforts to get a settlement” and had “torpedoed” an agreement in December.

But Mr Harper denied that ministers intervened in rail strike negotiations in December to stop a deal, saying: “That absolutely isn’t true.”

He added that the “very fair pay offer on the table” has been accepted by two of the trade unions on Network Rail, as he urged the RMT union to “get off the picket line” and do the same.

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RMT strike days will see approximately half of the network shut down, with just 20% of normal services expected to run. These trains will also start later and finish much earlier than usual, with journeys only possible between 7.30am and 6.30pm.

Mr Lynch said the government needs to set out its exact proposals to move forward the negotiations.

Referring to the transport secretary, he said: “I would go and meet him now if he wants, or he can come here and meet me, and we can hammer some things out.

“What we keep hearing is the same stuff from the government across the sectors that they want to facilitate an agreement, but they don’t actually do anything.”

Ahead of this week’s industrial action, the Department for Transport warned that passengers have “rightly had enough of rail strikes” – and called on unions to stop.

A spokesperson said: “The government has demonstrated it is being reasonable and stands ready to facilitate a resolution to rail disputes. It’s time the unions came to the table and played their part as well.

“Inflation-matching pay increases for all public-sector workers would cost everyone more in the long-term – worsening debt, fuelling inflation, and costing every household an extra £1,000.”